In certain types of surgical procedures, the use of surgical staples has become the preferred method of joining tissue and, as such, specially configured surgical staplers have been developed for these applications. For example, intra-luminal or circular staplers have been developed for use in a surgical procedure known as an anastomosis. Circular staplers useful for performing an anastomosis are disclosed, for example, in U.S. Pat. Nos. 5,104,025; 5,205,459; 5,285,945; and 5,309,927 which are each herein incorporated by reference in their respective entireties.
One form of an anastomosis comprises a surgical procedure wherein sections of intestine are joined together after a connecting section has been excised. The procedure requires joining the ends of two tubular sections together to form a continuous tubular pathway. Previously, this surgical procedure was a laborious and time consuming operation. The surgeon had to precisely cut and align the ends of the intestine and maintain the alignment while joining the ends with numerous suture stitches. The development of circular staplers has greatly simplified the anastomosis procedure and also decreased the time required to perform an anastomosis.
In general, a conventional circular stapler typically consists of an elongated shaft that has a proximal actuating mechanism and a distal stapling mechanism mounted to the shaft. The distal stapling mechanism typically consists of a fixed stapling cartridge containing a plurality of staples configured in a concentric circular array. A round cutting knife is concentrically mounted in the cartridge interior to the staples. The knife is moveable in an axial, distal direction. Extending axially from the center of the cartridge is a trocar shaft that has a staple anvil removably coupled thereto. The trocar shaft is moveable, axially, with respect to the cartridge and elongated shaft. The anvil is configured to form the ends of the staples as they are driven into it. The distance between a distal face of the staple cartridge and the staple anvil is controlled by an adjustment mechanism mounted to the proximal end of the stapler shaft. Tissue contained between the staple cartridge and the staple anvil is simultaneously stapled and cut when the actuating mechanism is activated by the surgeon.
When performing an anastomosis using a circular stapler, the intestine is typically stapled using a conventional surgical stapler with double rows of staples being emplaced on either side of a target section (i.e., specimen) of intestine. The target section is simultaneously cut as the section is stapled. After removing the specimen, the surgeon typically inserts the anvil into the proximal end of the lumen, proximal of the staple line. This is done by inserting the anvil head into an entry port cut into the proximal lumen by the surgeon. On occasion, the anvil can be placed transanally, by placing the anvil head on the distal end of the stapler and inserting the instrument through the rectum. The surgeon then ties the proximal end of the intestine to the anvil shaft using a suture or other conventional tying device. Next, the surgeon cuts excess tissue adjacent to the tie and the surgeon attaches the anvil to the trocar shaft of the stapler. The surgeon then closes the gap between the anvil and cartridge, thereby engaging the proximal and distal ends of the intestine in the gap. The surgeon next actuates the stapler causing several rows of staples to be driven through both ends of the intestine and formed, thereby joining the ends and forming a tubular pathway. Simultaneously, as the staples are driven and formed, the concentric circular knife blade is driven through the intestinal tissue ends, cutting the ends adjacent to the inner row of staples. The surgeon then withdraws the stapler from the intestine and the anastomosis is complete.
During the stapling process, however, it is often difficult for the surgeon to determine exactly when the knife blade has cut completely through the tissue. In an effort to provide the surgeon with some form of feedback concerning the travel of the knife, some prior staplers were fitted with a plastic washer or knife board designed to provide a “crunching” sound when the knife blade has traversed through the tissue to contact and breakthrough the washer. Often times, however, such feedback is insufficient.
Accordingly there is a need for an circular surgical stapler that has an improved system for providing an indication that the circular knife has completely cut through tissue.